the cycle superhighway from Tower Bridge to Canary Wharf has a lot of 2-way sections. Generally ok, although slow. Only crosses quiet road junctions without the assistance of traffic lights. This is just as well, as the right of way is either ambiguous or clearly not understood by all.
The only bad parts are
1) joining/leaving the cycle way at one end with is an uncontrolled cycleway/road/footpath mess.
2) the special bit where the 2 ways cycle way switches from one side of the road to the other, while also reversing the directions of the cycle lanes! It’s like road planning meets Scaletrix

They’re quite common here in Denmark, the end of my commute to work is one and I think your concerns are legitimate. Here drivers are much more aware and respectful to cyclists but I have very, very nearly been hit a few times by drivers not looking ahead of them.

common in holland. but then as a driver you have to give way a lot more. if you turn left or right in pretty much any direction, even if your motorised traffic lights are green you will have to give way to cyclists and pedestrians at a crossing. green means you may proceed. it does not infer any right of way, or priority.

Yep, loads here. The biggest problem I have with them are the roller skaters doing a Bodyform advert down the middle of the path.

I’m guessing, or at least hoping, that the parking will be the opposite side of the road to the cycle path!

The best place for them is definately where there are the least joining roads, paths etc, so they are IMO more suited to linking towns and villages than running along high streets although if it is the best way to segregate traffic due to road width, I can understand why they would do this.
The best solution is always to make the road wider when you build it, then you get results like this

Local council are proposing a radical shake-up of the high street near where we live. The 2 lanes each way down the main shopping part are to be changed to one lane each way, and some wild 2-way bike lne to be put down one side along with some parking (not sure how thats going to work!).

Never really had any experience of the 2-ways lanes, so not sure what to think. My intitial thoughts as a cyclist and as a driver is that left hand turns are going to be fun now there is a chance cyclists are going to be coming both ways at you on your left blind side.